The invention relates to a headlamp for a motor vehicle, in particular a front headlamp.
The prior art has disclosed the dynamic modification of the light distribution of a motor vehicle headlamp using mechanically movable light modules. In this way, it is possible to optimize the illumination of the region in front of the headlamp depending on various conditions. By way of example, it is possible to create cornering light, in which the headlamp shines into the curve during cornering. Likewise, it is possible to realize an antiglare high beam, in which certain regions of the high beam distribution that would lead to dazzling of traffic ahead or oncoming traffic are masked.
Conventional headlamps with the functionality of a dynamic light production are disadvantageous in that a complicated mechanism has to be integrated in the headlamp to this end.
It is an object of the invention to develop a headlamp for a motor vehicle that can be used to produce a dynamic component of the headlamp light in a simple manner.
This and other objects are achieved by a headlamp according to the invention for a motor vehicle such as an automobile, for example. The headlamp is preferably a front headlamp. The headlamp comprises a first illumination device and a second illumination device, which together produce a light distribution in front of the headlamp. The first illumination device serves to produce a static component of the light distribution, whereas the second illumination device is provided for producing a dynamic component of the light distribution. The term static component should be understood to mean that this component is unchanging within the light distribution, although the light distribution as a whole may be movable where necessary, for example in the case of a height adjustment of the headlamp in the motor vehicle. The term dynamic component should be understood to mean that this component is changeable over time within the light distribution in order to modify regions of the generated light distribution in terms of form and/or brightness as a result thereof.
The headlamp according to the invention is distinguished by virtue of the second illumination device comprising a multi-aperture projection display having an illuminant and a planar digital image generator, and an array of projection lenses. The digital image generator contains segments with a changeable division of the respective segment in transmissive and light-opaque regions. In a preferred variant, a transmissive region represents a region with a transmittance of 100%. Nevertheless, transmissive regions may also have a lower transmittance where necessary. By contrast, a light-opaque region always has a transmittance of 0%. The division in transmissive and light-opaque regions can be changed by virtue of the sizes of the transmissive and light-opaque regions being changed. However, a change of the division in transmissive and light-opaque regions is also present if the transmittance of transmissive regions is changed since the use of modified transmissive regions results in a different division. Further, the division in transmissive and light-opaque regions can be chosen within a segment in such a way that the segment is transmissive over the whole area thereof or light-opaque over the whole area thereof.
Each projection lens is assigned to a segment of the digital image generator, that is the number of segments corresponds to the number of projection lenses. When the array is illuminated using the illuminant, at least some of the segments are projected in front of the headlamp by the assigned projection lenses. A segment preferably comprises a multiplicity of pixels of the digital image generator, in particular at least 0.5 megapixels (500,000 pixels) of the digital image generator. As a result of this, it is possible to generate sharp-edged structures for a respective projection lens and in the corresponding projection.
The headlamp is configured in such a way that the digital image generator produces the dynamic light distribution during operation of the headlamp in the motor vehicle by changing the division of transmissive and light-opaque regions for at least some of the segments. Expressed differently, the headlamp comprises a control device for actuating the digital image generator in such a way that the dynamic component of the light distribution is produced.
The invention is based on the concept of using a multi-aperture projection display with a digital image generator, known per se, to generate dynamic light effects in the headlamp light. In contrast to the prior art, this requires no mechanism in the headlamp; instead, the change in the light distribution is effectuated purely by actuating a digital image generator.
In a preferred variant, the multi-aperture projection display also comprises an array of field lenses arranged between the illuminant and the planar image generator, in addition to the array of projection lenses. Preferably, one or more LEDs and/or, optionally, one or more of laser diodes, too, are used as illuminants in the projection display. The projection lenses of the multi-aperture projection display are preferably round lenses with a diameter of 2000 μm or less, in particular of 1000 μm or less (e.g. 800 μm).
In a particularly preferred embodiment, use is made in the headlamp according to the invention of a multi-aperture projection display as described in document DE 10 2009 024 894 A1 or in document DE 10 2011 076 083 A1. The entire disclosures of these documents are expressly incorporated by reference herein.
In a preferred embodiment, a low beam distribution, a high beam distribution and/or an antiglare high beam is producible using the headlamp according to the invention, depending on the mode of operation of the headlamp.
Preferably, the headlamp according to the invention is configured in such a way that the dynamic component of the light distribution produced by the second illumination device is produced during the operation of the headlamp in the motor vehicle depending on one or more driving parameters of the motor vehicle and/or one or more parameters in the surroundings of the motor vehicle.
In a particularly preferred embodiment, a dynamic light/dark boundary of a low beam distribution is produced using the second illumination device in one mode of operation of the headlamp, as a result of which a cornering light, known per se, can be realized. Alternatively, or additionally, the width of the light distribution can be modified using the second illumination device in one mode of operation of the headlamp and/or objects in the surroundings of the motor vehicle can be illuminated more strongly or less strongly. As a result of this, it is possible to realize one or more functionalities of a city light, freeway light, guide light, marking light, construction-site light and emergency maneuvering light, explained in the detailed description, and optionally other functionalities, too.
In a particularly preferred embodiment, the first illumination device of the headlamp according to the invention is a macro-optical illumination device without a multi-aperture projection display. Expressed differently, the first illumination device is an illumination device without lenses or an illumination device with one or more macro-optical lenses. Here, and below, a macro-optical lens should be understood to mean a lens that, in a plan view, has a minimal extent of 1 cm or more and, in particular, of 3 cm or more. Preferably, the first illumination device contains a maximum of 25 lenses and, in particular, at most five lenses. Depending on the configuration, the first illumination device can comprise an illumination unit with projection optics and/or an illumination unit with reflection optics. As a result of using the just-described first illumination device without a multi-aperture projection display, it is possible to realize a static component of the light distribution by a simple and cost-effective headlamp module.
In a further, particularly preferred configuration of the headlamp according to the invention, an LCD display, in particular a TFT display, is used as the digital image generator of the second illumination device.
Depending on the type of multi-aperture projection display used in the headlamp according to the invention, the transmissive regions in the respective segments can have a fixed transmittance of 100% or a variable positive transmittance of at most 100%. Expressed differently, the digital image generator can be used, where necessary, to change the division of the respective segments in transmissive and opaque regions by way of a variation of the transmittance of the transmissive regions.
In addition to the above-described headlamp, the invention further relates to a motor vehicle that comprises one or more of the headlamps according to the invention or one or more preferred variants of the headlamp according to the invention.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.